A budget deficit occurs when an entity (often a government) spends more money than it takes in. The opposite is a budget surplus.
This entry only concerns the government's deficits. These are important political issues. "Starve-the-beast" strategies usually lead to high budget deficits. Others, fiscal conservatives denounce deficit spending and advocate balanced budgets. Keynesians argue that under some circumstances, deficit spending is justified.
Note that the deficit is distinct from the government's debt (often confusingly called the national debt or public debt), which results from an accumulated deficit across a number of years. Often, a certain part of spending is dedicated to paying of debt with certain maturity, which can be refinanced by issuing new bonds. That is, a fiscal deficit leads to an increase in an entity's debt to others.
The United States
Historically, the United States government has tended to spend more than it takes in, with national debt that was close to $1,000,000,000 at the beginning of the 20th century. The budget for most of the 20th century followed a pattern of deficits during wartime and economic crises, and surpluses during periods of peacetime economic expansion. This pattern broke from fiscal years 1970 to 1997; although the country was nominally at peace during most of this time, the federal budget deficit accelerated, topping out (in absolute terms) at $290 billion for 1992. In 1998 - 2001, however, gross revenues exceeded expenditures. Subsequently the budget has returned to a deficit basis; the estimated U.S. deficit for fiscal year 2004 is $412.6 billion.
An issue about counting so-called "off-budget" items such as Social Security, which are presently running a large surplus, complicates discussion of budget deficits, as do the inevitable attempts by the party in power to downplay the deficit, while the other party exaggerates it. Nonetheless, the Social Security Administration does not see a large surplus -- while it is an example of an "off-budget" item, its own financial woes are generally recognized by experts on both sides of the aisle.
Related U.S. legislation